The present invention relates to oral dosage forms containing, as active ingredients, the biologically active proteins, granulocyte colony stimulating factor (G-CSF) and erythropoietin (EPO).
G-CSF is a hematopoietic factor which has been demonstrated to occur in the medium of cultures of human bladder carcinoma cell line 5637 (ATCC HT8-9) [Welte et al.: Proc. Natl. Acad. Sci. U.S.A., 82, 1526-1530 (1985)]. The DNA base sequence of the gene coding for this hematopoietic factor has been determined (Japanese Patent Application Laying-Out (KOHYO) No. 500636/88), thus making possible the production of G-CSF by the technique of genetic recombination.
G-CSF is effective in the treatment of common hematopoietic disorders, including hematopoietic disorders caused by chemotherapy or radiotherapy, and in bone marrow transplantation (Welte et al. supra).
Pharmaceutical preparations G-CSF with various stabilizers and additives for preventing its inactivation and adsorption to storage container walls have been the subject of numerous patent applications, e.g., Japanese Patent Application Laid-Open (KOKAI) No. 146826/88, for a preparation with an added surfactant; Japanese Patent Application Laid-Open (KOKAI) No. 146827/88 for a preparation with an added saccharide; Japanese Patent Application Laid-Open (KOKAI) No. 146828/88 for a preparation with an added high moleuclar weight compound; Japanese Patent Application Laid-Open (KOKAI) No. 146829/88 for a preparation with an added amino acid, sulfurated reducing agent, or antioxidant; and, Japanese Patent Application Laid-Open (KOKAI) No. 152326/88 for a preparation with an added protein. All these preparations, however, are in the form of injectable solutions.
A sustained-release preparation comprising G-CSF incorporated into a vehicle consisting of a biocompatible high polymer to prevent its inactivation and to extend the duration of its drug effects upon administration has been the subject of Japanese Patent Application Laid-Open (KOKAI) No. 91325/88. Furthermore, an enteric-coated preparation composed of G-CSF, a surfactant, a substance in a solid state at ordinary temperature and soluble in organic solvents, and an enteric material, designated for oral administration, has been reported [see, PCT Laid-Open Official Gazette (KOKAI-KOHO WO90/01329)].
Erythropoietin (EPO) is a hematopoietic glycoprotein hormone with an approximate molecular weight of 34,000 which is largely produced in and secreted by the kidneys and which functions to stimulate the differentiation of erythroblastic precursor cells into erythrocytes. EPO has been shown to be useful in erythropoietic therapy, represented by therapy for anemia, in man and other mammals.
Processes for obtaining EPO from natural sources, such as from urine of patients with aplastic anemia are known [Miyake et al., J. Biol. Chem., 252(15): pp. 5558-5564 (1977)]. Such methods, however, provide only a limited supply because of low yields and are therefore not suitable for industrial, large-scale production. Processes for production of EPO in high yields utilizing recombinant DNA techniques have been described. See, Japanese Patent Publication (KOKOKU) No. 17156/90 and U.S. Pat. No. 4,703,008.
Pharmaceutical preparations containing EPO have been the subject of patent applications, e.g., Japanese Patent Application Laid Open (KOKAI) No. 91131/86 and (KOKAI) No. 97229/86 for preparations with serum albumin, dextran or polyethylene glycol added to EPO for its stabilization or prevention of its adsorption to storage container walls and KOKAI No. 89627/87 for an intranasal preparation consisting of EPO and an aqueous and/or non-aqueous medium containing a surfactant.
Biologically active proteins are generally liable to be degraded by gastric acid and by enzymes in the gastrointestinal lumen or wall, and it is extremely difficult to have them absorbed from the digestive tract because of their molecular sizes and complicated molecular structures. Their clinical application has therefore been limited to parenteral administration by intravenous, subcutaneous or intramuscular injection. Parenteral administration entails problems of inflicting pain on the patient, of causing damage to the tissue at the site of injection, and of not readily permitting self-medication. Various proposals have been made for alternative methods of administration, including for example, intranasal administration [Pharm. Res., 21:105 (1989)], oral administration [Res. Commun. Pathol. Pharmacol., 63:53 (1989)], tracheal administration [Diabetes, 20:552 (1971)], transdermal administration [J. Pharm. Sci., 78:376 (1989)] and rectal administration [J. Pharm. Pharmacol., 33:334 (1981)]. These alternative methods all entail additional problems and none has proven to be of significant practical use.
The above problems associated with administration of biologically active proteins apply to G-CSF and EPO as well. Oral administration of these proteins would be greatly preferred for purposes of simplicity, avoidance of pain to the patient and clear potential for self-medication. However, proposals for oral administration of these substances have been extremely rare compared to proposals for other methods of dosing. See, e.g., Chem. Pharm. Bull, 30:2245 (1982) describing preparations in which the active ingredient is enclosed in liposomes; Japanese Patent Application (KOKUGAN) No. 190833/88 wherein the active ingredient is entrapped in microcapsules; and, Science, 233:1081 (1986) describing an active ingredient coated with azoaromatic copolymer.
Thus, there continues to exist a significant need in the art for new preparations of G-CSF or EPO suitable for oral administration with consequent obviation of the problems associated with parenteral administration.